Collaboration on documents is prevalent in both the workplace and at home. A person creating an electronic document often shares the document with other people, who may make changes, add comments and/or make suggestions (collectively, revisions, unless otherwise noted), before returning the document, in a marked-up form, to the original author. Electronic documents are accessed and manipulated by computer applications, such as Microsoft Word™, Corel WordPerfect™ and Adobe Acrobat™ or over the internet by services such as Writely™. Applications designed to access and manipulate electronic documents often contain functionality to capture and display the revisions made by different users. Such revisions are usually displayed in different colors—with each color denoting a different user—and lines which lead to side comments on the nature of the revision and the user who made them. Revisions made by a user are often treated as suggestions, which another user may choose to accept or reject. An acceptance or rejection does not usually eliminate the original revision visually. To the Contrary, acceptance or rejection of a revision often adds more graphics to the display of the revised document to show that a revision had been made by a certain user, and either accepted or rejected by another user. Thus, with every revision cycle where a user edits a document, the number of lines and colors that are added to the document in the form of markups may increase substantially. The resulting display of a revised document may easily confuse or overwhelm a person reviewing the revised document, which, after having been edited by a small number of users, may contain more colors and lines denoting revisions than actual content.
Conventional electronic document applications lack a sense of time and evolution in displaying revised documents. Humans are “wired” to view events in a chronological order, where they can follow a story board. When various users make changes to a document, they often follow a certain train of thought. One person's changes may be in response to a previous person's suggestions, which in turn, may be in response to another user's comments, and so forth. This chronology is often lost when all revisions are “collapsed” into a single document. Even though each user's additions, subtractions, approvals, rejections and comments may be noted in different colors, the presentation of so many changes at once may leave the reader unable to discern who-added-what-when-and-in-response-to-what. Some conventional electronic document applications allow the reader to choose to display a revised document in various discrete views. One view may be the original document before any revisions were made. Another view may the document in its final form, once all revisions have been approved or rejected. Another view may be the original document with all successive revisions before acceptance or rejection. Another view may be the changes done by one particular user. While being able to view a document in these various views is beneficial, it comes very short of giving a user a good sense for the chronology of changes and evolution of the revisions. For example, one word in a document may have been inserted by one user, rejected by another user who then substituted a different word in its place—a change that was rejected by another user who preferred to insert the original word back. The original author would look at the revised document and see their original word, but it would be surrounded by markings, such as colorful lines and side comments with the names of other users and actions they had taken. Such a display lacks a visual representation of the chronology of the changes made to the original document and a visual representation of the evolution of the document as it progressed from one user to the next.